Patent TW-318535-U (TW)
Title: Adjustable-length gas spring
Inventor: WOLF HERBERT
IPC: F16F9/56
Filed: 1997-01-31
Abstract: An adjustable length gas spring comprises a casing and a piston which i s disposed for displacement in the casing and joined to a piston rod. An externally operable adjusting valve is formed in the piston. Further, the piston is provided with a traction valve, which, upon application of tractive force from outside, cancels any blockage of the piston. <SDOCL LA=EN> -12- The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows: 1.; An adjustable-length gas spring, comprising: a casing which has a central longitudinal axis and is filled with a liquid pressure fluid; a guide and seal unit which closes the casing at a first end; a piston rod for sealed guidance through the guide and seal unit out of the first end of the casing; a piston for sealed guidance in the casing, the piston being joined to the piston rod; a first divisional interior chamber which is formed between the piston and the guide and seal unit; a second divisional interior chamber which is defined by the piston and turned away from the first divisional interior chamber; an adjusting valve which is disposed in the piston and interconnects the first and second divisional interior chamber having: a valve control pin which is displaceable in a direction of the central longitudinal axis; a valve tray which is mounted on the valve control pin; ; a first sealing seat; and a first sealing contact surface which cooperates with the first sealing seat; -13- the first sealing seat and the first sealing contact surface being liftable off each other by means of the valve control pin; a traction valve, which is disposed on the piston, for interconnection of the first and second divisional interior chamber when tractive force acts between the piston rod and the casing, the traction valve having: a second sealing seat; and a second sealing contact surface that cooperates with the second sealing seat; the second sealing seat and the second sealing contact surface, upon increase of pressure in the first divisional interior chamber, being liftable off each other while the traction valve opens; ; wherein the adjusting valve and the traction valve have a joint sliding bush which is guided for displacement on the valve control pin in the direction of the central longitudinal axis and bears either the first or second sealing contact surface or the first or second sealing seat. 2. A gas spring according to claim 1, wherein the adjusting valve, when shut off, has a surface F37 which is in connection with the first divisional interior chamber; wherein the traction valve, when shut off, has a surface F38 which is in connection with the first divisional interior chamber; and wherein F38 > F37 applies. -14- 3. A gas spring according to claim 1 or 2, wherein the sliding bush has passages which are allocated to the adjusting valve and the traction valve. 4.; A gas spring according to claim 1, 2 or 3, wherein the sliding bush supports a valve disk on which the first sealing contact surface and the second sealing contact surface are formed. 5. A gas spring according to claim 4, wherein the valve disk comprises sealing material on both sides. 6. A gas spring according to claim 4 or 5, wherein a gap is formed between the valve disk and an inside wall that defines the first and second divisional interior chambers. 7. A gas spring according to any one of claims 1 to 6, wherein the first sealing seat has the shape of a circular ring and a diameter D24; wherein the second sealing seat has the shape of a circular ring and a diameter D32; and wherein D32 > D24 applies. -15- 8.; A gas spring according to any one of claims 1 to 7, wherein an equalization chamber is provided, which is filled with compressed gas and connected to one of the divisional interior chambers. 9. A gas spring according to claim 8, wherein the first and second divisional interior chambers are formed in an internal cylinder which, concentrically of the central longitudinal axis, is enveloped by a casing; wherein an annular chamber, which is formed between the casing and the internal cylinder, is divided by a dividing piston into a first division al annular chamber filled with compressed gas and a second divisional annular chamber filled with liquid pressure fluid; and wherein the second divisional annular chamber, which is filled with pressure fluid, is permanently connected to the first divisional interior chamber via a connecting